pub fn doppler_factor_longitudinal_from_beta(beta: f64) -> Option<f64>Expand description
Computes the longitudinal relativistic Doppler factor D = sqrt((1 + β) / (1 - β)).
Positive beta means the source is approaching the observer. Negative beta means the source
is receding.
Returns None when beta is not finite, when beta <= -1.0 or beta >= 1.0, or when the
computed factor is not finite.